The recent demolition of a North Roxbury Drive residence where Gershwin lived, wrote and entertained Hollywood royalty is just the latest example of how difficult it can be to preserve the past in a city where residents are accustomed to doing as they wish.

Beverly Hills offers a trove of distinctive homes designed by noted architects, many with legacies that date to Hollywood's Golden Age. But architectural and cultural heritage has often proved no match for the nouveaux riches of Beverly Hills.

"Tastes have changed," said Stan Smith, managing director of Teles Properties, a high-end real estate firm. "The kinds of houses people want today aren't reflected in the old stock."

Some of the older homes lack the style and amenities today's luxury buyers want — great rooms, entertainment centers, cavernous closets, restaurant-quality kitchens and vast bedroom suites. Rooms in even the most opulent of older Beverly Hills homes can feel cramped by modern high-end standards.

Perhaps no one has torn down and rebuilt more homes in Beverly Hills than Hamid Omrani.

The Iranian-born Omrani, who estimates he has designed 150 houses in the city, said many of his clients dislike the Spanish, Tudor and other revival styles of Beverly Hills' early homes. For them, remodeling is unappealing. They want to maximize home size, often reducing outdoor space in favor of more bedrooms and more expansive living areas.

"They prefer to buy and demolish," he said.

For the year to date in Los Angeles County, Beverly Hills 90210 has the second-highest median price ($2.6 million) for existing single-family homes in Los Angeles County, after only Santa Monica 90402 ($2.9 million), according to DataQuick, a real estate firm based in San Diego.

The tear-down phenomenon is hardly new. Beverly Hills residents have for decades razed houses that earlier generations considered grand to make way for more lavish residences, many of them stucco-and-glass boxes with the vague aura of Italian villas.

They featured flat roofs, second-floor balconies with tall windows, soaring entry doors embellished by metalwork and columns, lots and lots of columns. Collectively, these houses took on the sobriquet "Persian palaces" because they appealed to the Iranian-born families that are estimated to make up more than one-sixth of Beverly Hills' 34,000 residents.

Initially, many of these new manses overwhelmed their neighbors, but now they have plenty of imposing company.

Many structures associated with celebrities or designed by noted architects were among those toppled by bulldozers, including John Lautner's curvaceous Shusett House. After a home created by modernist Richard Neutra came perilously close to meeting that fate, Beverly Hills finally got serious about preserving its architectural and cultural legacy.

The city enacted an ordinance early last year, then quickly embraced tax breaks to foster neighborhood preservation and designated 14 local landmarks, including the Beverly Hills Hotel, Greystone Mansion, the Witch's House and City Hall. The city is also conducting a citywide survey to identify potentially significant houses.

In Trousdale Estates, where early homes were designed by Paul Revere Williams, Wallace Neff and Harold Leavitt, "we found 200 properties of note, out of 535," said Steven M. Price, a historian who is helping to conduct the inventory.

The actions have pleased critics who had long deemed the city too willing to sacrifice significant structures to make way for mixed-breed palazzos or undistinguished apartment buildings. Others say it is unfair to dictate what an owner may or may not do to his property.

The Ira Gershwin house fell between the cracks, city officials say.

The now-leveled house at 1021 N. Roxbury Drive was decidedly "old stock." Lyricist Gershwin and his wife, Lee, hired John Elgin Woolf to extensively remodel the house in his trademark Hollywood Regency style. Because Woolf appears on the city's list of local master architects, the demolition application should have been flagged for further review. But city employees who granted the permit apparently were unaware of Woolf's connection.